Before we jump into a debate about the environmental costs of eating meat , here are three things you should know :

1 . I 've experimented with vegetarianism twice , but it 's never really stuck . Round one ended when I had a dream about a spicy chicken sandwich from Wendy 's , and then woke up to march zombie-style to that fast-food restaurant to order it . Round two may or may not have ended with the brunch I had Sunday , I 'm still not sure .

2 . I ate chicken chilaquiles for brunch on Sunday . It was delicious .

Therefore , 3 . This is not an anti-meat polemic .

But I have been thinking in recent weeks about our relationships with animals and what our diets mean for the health of the environment . It started while I was doing research for a story on illegal animal trafficking , and I was reading books , including Dana Goodyear 's `` Anything that Moves '' -- about how the American foodie scene is trending toward the bizarre and endangered -LRB- witness the 2010 bust of a California restaurant serving whale -RRB- -- and Jonathan Safran Foer 's `` Eating Animals , '' which argues , in part , that one can not eat meat and also earnestly claim to be an environmentalist .

'' -LRB- S -RRB- omeone who regularly eats factory-farmed animal products can not call himself an environmentalist without divorcing that word from its meaning , '' he wrote in that book .

Since it 's Earth Day , I thought that last point might merit some dissection . Is it possible to eat meat in modern-day America , consider yourself an environmentalist and sleep soundly without being a hypocrite ? Or , as Foer argues , are those terms increasingly incongruous ?

Eatocracy : Tips for eating green on Earth Day

I called up a few experts and asked your advice on this topic . As one of my Facebook friends was smart to point out , it 's probably not a good idea to be in the business of telling people `` what they are or are not . '' Environmentalism takes many forms and encompasses a range of issues . I 'm not willing to say a person can not be an environmentalist and also an omnivore . -LRB- If you ride a bike and eat steak , is that better or worse than being a vegetarian who drives a Hummer ? -RRB- But I would hope that person has thought through the very real environmental consequences of meat consumption .

Animal rights aside , there are plenty to consider . Here are a few :

1 . Raising animals for meat is much less efficient than growing vegetables : Think back to those food chain diagrams from elementary school . Animals are higher on the food chain than plants , and therefore they take more land , food and water to grow for our consumption . The difference in efficiency is n't negligible : Raising a kilogram of beef requires 15,500 liters of water , according to waterfootprint.org . An equivalent amount of bread requires only 1,300 liters of water ; bananas use 860 ; and tomatoes consume just 180 liters , or about 1 % of the water required for beef . -LRB- Chocolate , by the way , is actually worse than all of these , requiring 24,000 liters ; but it 's clear that a vegetarian diet is far more water - and energy-efficient than one that includes meat . -RRB-

At a time when rivers in the American Southwest are running dry because of drought and climate change , it 's worth considering the impact our eating habits have on water use .

The same is true for land . Because growing vegetables is more land-efficient than growing meat , we would need to eat far less meat in order to avoid taking over more forests for farms , said Robert Howarth , a professor of ecology and environmental biology at Cornell University . To be sustainable , America needs to eat about half the meat it does today , he said . That would return us to about 1940s consumption levels . Per capita meat consumption in the United States appears to have peaked around the year 2000 at more than 180 pounds of meat per person per year , or about half a pound each day , according to the Earth Policy Institute .

It 's fallen slightly since then , which is good news .

2 . Animal agriculture pollutes the water : Last summer , like pretty much every summer , there was a `` dead zone '' in the Gulf of Mexico the size of Connecticut . Blame agriculture , including animal agriculture , for that disturbing phenomenon , which is caused when phosphorus and nitrogen from chemical fertilizer and manure run down the Mississippi River and into the gulf . Much of the fertilizer that ends up in that watershed is used to grow corn , 80 % of which is being produced to feed livestock and fish , according to National Corn Growers Association figures cited by EPA . The amount of manure that animal farms create is also staggering -- U.S. federal agencies estimate livestock and poultry `` generate '' about 500 million tons of manure per year -- and has serious consequences for the health of rivers and groundwater .

3 . Eating meat adds to your greenhouse gas footprint : Finally , eating animals , like doing almost anything , contributes to a person 's greenhouse gas footprint . The United Nations estimates animal agriculture accounts for 14.5 % of human greenhouse gas emissions , with the main source of those emissions -- 45 % of the total -- being the fossil fuels used while growing and fertilizing crops to feed the animals . There 's some debate about how much animal agriculture contributes to climate change overall . But there 's no doubt it has a sizable impact , and more so than plant agriculture . According to the Natural Resources Defense Council , eating a half-pound of beef creates more than 7 pounds of carbon-dioxide-equivalent gases . Pork and chicken are better , creating about 2 pounds and half a pound , respectively . Potatoes , apples and asparagus are better still , creating a tiny fraction of a pound of greenhouse gases .

So : Knowing all that , I would encourage you to consider giving up meat -- or even just one of the most resource-intensive meats , like beef -- for Earth Day . See how it goes , and maybe you can make it a habit . There are many other worthy efforts you could make to protect the environment , of course . You could ride a bike , take a train , turn off the heat or AC . But giving up meat for a day is an easy and meaningful one . `` If all Americans eliminated just one quarter-pound serving of beef per week , the reduction in global warming pollution would be equal to taking 4 to 6 million cars off the road , '' according to the Natural Resources Defense Council .

You might find it 's awful and decide to focus your future efforts elsewhere . Or , like me , you might find it 's not so bad . I 'm not going to make any bold pronouncements about my eating habits besides the fact that I 'm going to try to eat less meat . -LRB- I like TreeHugger founder Graham Hill 's idea of eating meat only on the weekends ; and singer Paul McCartney 's idea of Meat Free Mondays . -RRB-

I travel frequently , and value flexibility , so I 've never really wanted to be too strict about my diet in the long term . But one day ? One week ? One month ? It 's not that hard .

To the minority of vegans and vegetarians who like to proselytize about their eating habits , I 'm sure that seems like an annoying cop-out . But there are plenty of environmentalists who advocate a middle-road approach to meat consumption .

`` Certainly there are modest steps we can all take that can really have a significant benefit if a lot of people did them , '' said Erik Olson , a health and food expert at NRDC , the environmental group . `` We often fall into this mistaken all-or-nothing mentality . ''

I like that approach . It 's one more people are likely to stomach .

And it 's one that -- even for a day -- can have real impact .

@highlight

A growing body of evidence shows eating meat has environmental consequences

@highlight

John Sutter says readers should consider giving up meat on Earth Day

@highlight

He writes that meat production pollutes water and contributes to climate change

@highlight

Expert : Eating less meat helps ; it does n't have to be ` all or nothing '